Refrigeration cycle

Abstract

To provide a refrigeration cycle which is capable of reducing power consumption while solving the problems of hunting and oil circulation. The refrigeration cycle is formed by combining an expansion valve that controls the flow rate of refrigerant supplied to an evaporator such that refrigerant at the outlet of the evaporator always maintains a predetermined level of superheat, in normal times, and is equipped with a minimum flow rate-securing device capable of allowing the refrigerant to flow at a predetermined minimum flow rate when the flow rate is most restricted, with a variable displacement compressor.

1 . A refrigeration cycle including a variable displacement compressor, and an evaporator, comprising: 
 an expansion valve that is capable of controlling a flow rate of refrigerant supplied to the evaporator such that the refrigerant at an outlet of the evaporator maintains a predetermined level of superheat in normal times, and allowing the refrigerant to flow at a predetermined minimum flow rate when the flow rate is most restricted.    
   
   
       2 . The refrigeration cycle according to  claim 1 , wherein the variable displacement compressor senses suction pressure, and controls pressure in a crankcase in response to the sensed suction pressure such that the suction pressure is held constant, and 
 wherein the expansion valve is a thermostatic expansion valve of a normally-charged type that has a valve section formed with a bypass passage.    
   
   
       3 . The refrigeration cycle according to  claim 2 , wherein the bypass passage has a size large enough to allow the refrigerant to flow at a flow rate required at least for preventing hunting.  
   
   
       4 . The refrigeration cycle according to  claim 1 , wherein the variable displacement compressor senses differential pressure between discharge pressure and suction pressure, and controls pressure in a crankcase in response to the sensed differential pressure such that the differential pressure is held constant, and 
 wherein the expansion valve is a thermostatic expansion valve of a normally-charged type that has a valve section formed with a bypass passage.    
   
   
       5 . The refrigeration cycle according to  claim 4 , wherein the bypass passage has a size large enough to allow the refrigerant to flow at a minimum flow rate required at least for oil circulation.  
   
   
       6 . The refrigeration cycle according to  claim 1 , wherein the variable displacement compressor senses suction pressure and controls pressure in a crankcase in response to the sensed suction pressure such that the suction pressure is held constant, and 
 wherein the expansion valve is a solenoid-driven electronic expansion valve that can be controlled such that the solenoid-driven electronic expansion valve is not closed.